I will sling some BS for the sport of it. All things in existence are subject and coexist in the same spectrum of frequencies. Our soul is the center band (radio station of sorts) of our collective aura which each individual feels as I. Imagine the Sun as the Major harmonic frequency, Jupiter as the next biggest harmonic stabilizer, earth, the moon, our region, our city, etc. etc. Our minds are a powerful radiator of frequency, the more minds tuned in to the same overtones of society, the more we influence each other and drown out the outlier spikes and chaotic frequency disruptions. When awake, we are more subject to external stimuli, or project our own emotional frequency (like stress) which can lead us to losing the synchronicity. When asleep or trained to enter the proper mental state, we can fall deeply into the rhythm of our subconscious and loose ourselves to the collective and free ourselves of our Makyo (the earthly distractions keeping us from fully submersing our conscious into the noosphere.
That scene in End of Evangelion where they're all in each other's minds
I am not entirely sure if it's related or not but I'm working on a story with a similar concept. A man is trapped in a room inside his mind for a very long time. The room is shaped according to his personality. But how would that look, exactly? I imagine him to be an intellectual and an inventor. Therefore, there would be books and electronic compoments in the room. As the time goes on the room begins to break down. The walls crack, lights dim, objects expire, darkness takes over as his mind darkens and he goes insane. Not completely insane. He still remembers who he is and his memory is intact. But his goals, manners etc. have changed. But is simply making the room decay enough to portray the state of his mind? The room is still recognizable which means he still has qualities from his former self. And that is true. But I also plan on showing a larger scale place that surrounds the room. I am conflicted wheather those areas should look similar to his room or look different than it to imply most things in his mind have changed?
There are many resources to research for inspiration here as similar concepts exists outside of science fiction.
Read up on the concept of the astral plane and by extension, astral projection.
https://en.wikipedia.org/wiki/Astral_plane
https://en.wikipedia.org/wiki/Astral_projection
